Forming catalytic sites from reducible silver complexes

ABSTRACT

A non-aqueous metal catalytic composition includes (a) a silver complex comprising reducible silver ions, (b) an organic phosphite, (c) an oxyazinium salt silver ion photoreducing agent, (d) a hindered pyridine, (e) a photocurable component, a non-curable polymer, or combination of a photocurable component and a non-curable polymer, and (f) a photosensitizer different from all components (a) through (e) in the non-aqueous metal catalytic composition, in an amount of at least 1 weight %. This non-aqueous metal catalytic composition can be used to form silver metal particles in situ during suitable reducing conditions. The silver metal can be provided in a suitable layer or pattern on a substrate, which can then be subsequently subjected to electroless plating to form electrically-conductive layers or patterns for use in various articles or as touch screen displays in electronic devices.

RELATED APPLICATIONS

Reference is made to the following copending and commonly assignedpatent applications, the disclosures of which are incorporated herein byreference:

U.S. Ser. No. 14,571,375 (filed on Dec. 16, 2014, by Shukla and Donovan)entitled “Forming Silver Catalytic Sites from Silver-PhosphiteCarboxylates”;

U.S. Ser. No. 14,571,410 (filed on Dec. 16, 2014, by Shukla and Donovan)entitled “Forming Silver Catalytic Sites from Reducible Silver-Oximes”;

U.S. Ser. No. 14/571,439 (filed on Dec. 16, 2014, by Shukla and Donovan)entitled “Forming Catalytic Sites from Reducible Silver-HeterocyclicComplexes”;

U.S. Ser. No. 14/571,363 (filed on Dec. 16, 2014, by Shukla) entitled“Non-aqueous Metal Catalytic Composition with Oxyazinium PhotoreducingAgent”;

U.S. Ser. No. 14/571,393 (filed on Dec. 16, 2014, by Shukla) entitled“Non-aqueous Metal Catalytic Composition with SilverCarboxylate-Trialkyl(Triaryl)phosphite Complex”;

U.S. Ser. No. 14/571,419 (filed on Dec. 16, 2014, by Shukla) entitled“Non-aqueous Metal Catalytic Composition with Silver-Oxime Complex”;

U.S. Ser. No. 14/571,462 (filed on Dec. 16, 2014, by Shukla) entitled“Non-aqueous Metal Catalytic Composition with Silver N-HeterocycleComplex.”;

FIELD OF THE INVENTION

This invention relates to a method for forming silver particles in-situfrom reducible silver ions that are provided from a coating or patternof a non-aqueous metal catalytic composition containing a silver complexcontaining reducible silver ions, a silver ion photoreducingcomposition, and a photocurable component or non-curable polymer. Theresulting silver particles in the layer or coating can be used directlyas electrically-conductive materials or as “seed” catalytic sites forelectroless plating of a suitable electrically-conductive metal.

BACKGROUND OF THE INVENTION

Rapid advances are occurring in various electronic devices especiallydisplay devices that are used for various communicational, financial,and archival purposes. For such uses as touch screen panels,electrochromic devices, light emitting diodes, field effect transistors,and liquid crystal displays, conductive films are essential andconsiderable efforts are being made in the industry to improve theproperties of those conductive films.

There is a particular need to provide touch screen displays and devicesthat contain improved conductive film elements. Currently, touch screendisplays use Indium Tin Oxide (ITO) coatings to create arrays ofcapacitive areas used to distinguish multiple point contacts. ITOcoatings have significant short comings. Indium is an expensive rareearth metal and is available in limited supply from very few sources inthe world. ITO conductivity is relatively low and requires short linelengths to achieve adequate response rates. Touch screens for largedisplays are broken up into smaller segments to reduce the conductiveline length to an acceptable resistance. These smaller segments requireadditional driving and sensing electronics. In addition ITO is a ceramicmaterial, is not readily bent or flexed, and requires vacuum depositionwith high processing temperatures to prepare the conductive layers.

Silver is an ideal conductor having conductivity 50 to 100 times greaterthan ITO. Silver is used in many commercial applications and isavailable from numerous sources. It is highly desirable to makeconductive film elements using silver as the source of conductivity.

Numerous publications describe the preparation ofelectrically-conductive films formed by reducing a silver halide imagein silver halide emulsions in the form of electrically-conductive gridnetworks having silver wires having sizes of less than 10 μm. Variousefforts have been made to design the silver halide emulsions andprocessing conditions to optimize such electrically-conductive gridnetworks and the methods for making them.

For example, improvements have been proposed for providingelectrically-conductive grid patterns from silver halides by optimizingthe silver halide emulsions as well as finding optimized processingsolutions and conditions to convert latent silver images into silvermetal grid patterns. The precursors used to provide the conductive filmscan comprise one or more silver halide emulsion layers on opposing sidesof a transparent substrate, along with optional filter layers andhydrophilic overcoats.

While these processes and articles can provide desiredelectrically-conductive films, optimizing the design of both theprecursors and processing procedures requires considerable effort inorder to achieve the exacting features required inelectrically-conductive films to be incorporated into touch screendisplays.

Other industrial approaches to preparing electrically-conductive filmsor elements have been directed to formulating and applying photocurablecompositions containing dispersions of metal particles such as silvermetal particles to substrates, followed by curing of the photocurablecomponents in the photocurable compositions. The applied silverparticles thus act as catalytic (seed) particles for electrolesslyplated electrically-conductive metals. Useful electrically-conductivegrids prepared in this manner are described for example in WO2013/063183 (Petcavich), WO 2013/169345 (Ramakrishnan et al.). Otherdetails of a useful manufacturing system for preparing conductivearticles especially in a roll-to-roll manner are provided inPCT/US/062366 (filed Oct. 29, 2012 by Petcavich and Jin).

Using these methods, photocurable compositions containing silverparticles can be printed and cured on a suitable transparent substratefor example a continuous roll of a transparent polyester, and thenelectroless plating can be carried out. These methods require that highquantities of silver particles be dispersed within the photocurablecompositions in a uniform manner so that coatings or printed patternshave sufficiently high concentration of catalytic sites. This generallycannot be achieved without carefully designed dispersants and dispersingprocedures and such dispersants can be expensive and hard to use in amanner to provide reproducible products in a high speed manufacturingoperation. Without effective dispersing, silver particles can readilyagglomerate, leading to less effective and uniform application ofcatalytic metal patterns and electroless plating. It is thereforedifficult to provide uniform electrically-conductive films having thedesired electrically-conductive metal patterns.

U.S. Patent Application Publication 2007/0261595 (Johnson et al.)describes a method for electroless deposition on a substrate that usesan ink composition containing silver as a reducible silver salt andfiller particles. After reducing the reducible silver ions, suchcompositions can be cured for improved adhesion to the substrateespecially if the compositions contain an UV-curable monomer oroligomer.

U.S. Pat. No. 7,875,416 (Park et al.) describes photosensitivecompositions comprising a multifunctional epoxy resin, a photoacidgenerator, an organic solvent, and silver particles.

A common coordinating ion to form organic silver complexes is carboxylicacid [Prog. Inorg. Chem., 10, 233 (1968)]. However, silver-carboxylatecomplexes are generally sensitive to light and hardly soluble in organicsolvents [U.S. Pat. No. 5,491,059 of Whitcomb and U.S. Pat. No.5,534,312 of Hill et al.] and have a high decomposition temperature.Thus, such complexes have little utility in spite of ready availability.To solve this problem, several methods have been proposed for example,in Ang. Chem., Int. Ed. Engl., 31, p. 770 (1992), Chem. VaporDeposition, 7, 111 (2001), Chem. Mater., 16, 2021 (2004), and U.S. Pat.No. 5,705,661 (Iwakura et al.). Among such methods are those usingcarboxylic acid compounds having long alkyl chains or including aminecompounds or phosphine compounds. However, the silver derivatives knownthus far are limited and have insufficient stability or solubility.Moreover, they have a high decomposition temperature needed to be usefulfor pattern formation and are decomposed slowly.

U.S. Pat. No. 7,682,774 (Kim et al.) describes other photosensitivecompositions comprising silver fluoride organic complex precursors ascatalyst precursors. This patent describes the use of polymer derivedfrom a monomer having a carboxyl group and a co-polymerizable monomerthat may provide polymeric stability and developability of the resulting“seed” silver catalyst particles used for electroless plating.

Despite the various techniques described in the art, there remains aneed for an improved means for providing silver catalytic (seed)particles for electroless plating in the formation ofelectrically-conductive patterns in a reproducible and high-speed mannersuitable for continuous high-speed production. It is particularlydesirable to provide a method for high-speed production ofelectrically-conductive patterns without the need for complicated anduncertain dispersing procedures for high concentrations of silver metalparticles.

SUMMARY OF THE INVENTION

The present invention provides a method for providing an article, themethod comprising:

providing a metal catalytic layer or a metal catalytic pattern composedof a non-aqueous metal catalytic composition on a substrate, thenon-aqueous metal catalytic composition comprising:

-   -   (a) a silver complex comprising reducible silver ions, in an        amount of at least 2 weight %,    -   (b) an organic phosphite in an amount of at least 2 weight %,    -   (c) an oxyazinium salt silver ion reducing agent in an amount of        at least 2 weight %,    -   (d) a hindered pyridine in an amount of at least 5 weight %,    -   (e) a photocurable composition, non-curable polymer, or        combination of a photocurable component and a non-curable        polymer, and    -   (f) a photosensitizer different from all of components (a)        through (e) in the non-aqueous metal catalytic composition, in        an amount of at least 1 weight %,    -   all amounts being based on the total amount of components (a)        through (f) in the non-aqueous metal catalytic composition,    -   to provide a precursor article comprising the metal catalytic        layer or the metal catalytic pattern composed of the non-aqueous        metal catalytic composition.

In some embodiments, the method further comprises:

-   -   photoreducing the reducible silver ions to silver particles in        the metal catalytic layer or the metal catalytic pattern.

Moreover, these embodiments can also further comprise, afterphotoreducing the reducible silver ions to silver particles:

-   -   electrolessly plating a metal other than silver onto the silver        particles in the metal catalytic layer or metal catalytic        pattern.

In other embodiments, after photoreducing the reducible silver ions tosilver particles, the method can further provide:

-   -   removing organic phosphite from the metal catalytic layer or        metal catalytic pattern, and    -   electrolessly plating a metal other than silver onto the silver        particles in the metal catalytic layer or metal catalytic        pattern.

The advantage of the present invention is to provide a source of silverparticles that can be used as electrically-conductive silver metal orcatalytic (seed) sites for electroplating without having to dispersesilver particles in various photocurable compositions. The presentinvention avoids the need to carefully disperse silver particles andpotential agglomeration in coating or printing compositions (“inks”) by“creating” or generating the silver particles in-situ as seed catalystsafter a photocurable composition has been coated or printed. Thus, thesilver particles are generated in situ from reducible silver ions thatcan be provided in silver complexes in coated or printed non-aqueousmetal catalytic compositions. Using this means for producing silvermetal particles reduces possible operator errors during dispersingprocesses and reduces defects in producing electrically-conductivepatterns. These advantages are particularly useful in high-speedmanufacturing operations such as roll-to-roll methods in which theapplication, curing, and electroless plating can be carried out in acontinuous manner.

Thus, important differences between the present invention and what isknown in the art include at least the following:

-   -   1) A number of silver containing complexes are known but where        formulations are to be designed with high concentrations of        pre-formed silver particles, such as loaded pastes and inks, the        formulations become highly complex in order to make them stable        as dispersions of the silver particles. The present invention        avoids this problem by enabling the formation of high        concentrations of silver particles for various photocurable        compositions.    -   2) Photochemical methods used to generate silver nanoparticles        use silver nitrate and methyl diethanolamine that are starting        materials that show poor stability (that is, the silver ions are        reduced thermally) and cause gelling of polymerizable monomers        by the silver ions. The present invention avoids this problem by        forming silver particles in situ and avoids the use of unstable        reactants.    -   3) Known photochemical methods used to generate silver        nanoparticles have little practical utility as they use silver        nitrate as a starting material and this salt exhibits poor shelf        keeping or dark stability. The present invention avoids this        problem by using silver complexes and photocurable compositions        that are light stable precursors for photogenerating silver        particles in thin films or other useful formats.    -   4) Other known photochemical methods used to generate silver        nanoparticles use silver fluoride organic complex precursors as        catalyst precursors. For example, U.S. Pat. No. 7,682,774 (noted        above) describes the use of a carboxyl group containing polymer        that has an acid value of 90 to 700 mg KOH/g. The described        process additionally requires first a heating at 100° C.,        reduction of the silver fluoride complex, and then electroless        plating. The present invention provides a much simpler process        and is not restricted to carboxyl-containing polymers and        oligomers that exhibit various problems described above.    -   5) Known compositions containing silver nanoparticles generally        contain ligands or dispersing agent that provide only        stabilization or solubilization of the particles. The present        invention avoids this by providing stabilized silver complexes        in photocurable compositions that provide an easy way to        generate silver particles without the need for separate        stabilizing ligands or dispersing agents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows absorption spectra showing silver plasmon band formationupon in situ photogeneration of silver nanoparticles using the silvercomplex prepared in Invention Example 1 below.

FIG. 2 is a micrograph of an article prepared according to the presentinvention in Invention Example 2 below.

DETAILED DESCRIPTION OF THE INVENTION

The following discussion is directed to various embodiments of thepresent invention and while some embodiments can be desirable forspecific uses, the disclosed embodiments should not be interpreted orotherwise considered to limit the scope of the present invention, asclaimed below. In addition, one skilled in the art will understand thatthe following disclosure has broader application than is explicitlydescribed with the discussion of any one embodiment.

Definitions

As used herein to define the components of the various non-aqueous metalcatalytic compositions, unless otherwise indicated, the singular forms“a,” “an,” and “the” are intended to include one or more of thecomponents (that is, including plurality referents).

Each term that is not explicitly defined in the present application isto be understood to have a meaning that is commonly accepted by thoseskilled in the art. If the construction of a term would render itmeaningless or essentially meaningless in its context, the termdefinition should be taken from a standard dictionary or have customaryor commonly understood meaning.

The use of numerical values in the various ranges specified herein,unless otherwise expressly indicated otherwise, are considered to beapproximations as though the minimum and maximum values within thestated ranges were both preceded by the word “about.” In this manner,slight variations above and below the stated ranges can be used toachieve substantially the same results as the values within the ranges.In addition, the disclosure of these ranges is intended as a continuousrange including every value between the minimum and maximum values.

Unless otherwise indicated, the term “weight %” refers to the amount ofa component or material based on the total solids of a non-aqueous metalcatalytic composition, formulation, solution, or the % of the dry weightof a metal catalytic layer or metal catalytic pattern. Unless otherwiseindicated, the percentages can be the same for either a dry metalcatalytic layer or metal catalytic pattern, or for the total solids ofthe formulation or non-aqueous metal catalytic composition used to makethat metal catalytic layer or metal catalytic pattern.

As used herein, the terms “curing” and “photocuring” mean thepolymerization of functional oligomers and monomers, or even polymers,into a crosslinked polymer network as initiated by suitable irradiation.Curing can be polymerization of unsaturated monomers or oligomers asphotocurable components in the presence of crosslinking agents.

The photocurable components can be photocured when irradiated withsuitable radiation, for example ultraviolet (UV) or visible radiationhaving a wavelength of at least 150 nm and up to and including 750 nm.

Unless otherwise indicated, the terms “non-aqueous metal catalyticcomposition” and “metal catalytic composition” are considered to be thesame.

Unless otherwise indicated, the term “non-aqueous” as applied to themetal catalytic composition means that liquids in such compositions arepredominantly organic solvents and water is not purposely added and maybe present in an amount of less than 10 weight %, or particular of lessthan 5 weight %, or even less than 1 weight %, of the total non-aqueousmetal catalytic composition weight. In most instances, the presence ofwater can adversely affect the silver complexes used in the presentinvention.

Average dry thickness of metal catalytic layers or metal catalyticpatterns described herein can be the average of at least 2 separatemeasurements taken, for example, using electron microscopy.

Similarly, the average dry thickness or width of lines, grid lines, orother pattern features described herein can be the average of at least 2separate measurements taken, for example, using electron microscopy.

Unless otherwise indicated, the term “group” particularly when used todefine a substituent of a define moiety, can itself be substituted orunsubstituted (for example and alkyl group” refers to a substituted orunsubstituted alkyl). Generally, unless otherwise specifically stated,substituents on any “groups” referenced herein or where something isstated to be possibly substituted, include the possibility of anygroups, whether substituted or unsubstituted, which do not destroyproperties necessary for the utility of the component or non-aqueousmetal catalytic composition. It will also be understood for thisdisclosure and claims that reference to a compound of a particulargeneral structure includes those compounds of other more specificformula that fall within the general structural definition. Examples ofsubstituents on any of the mentioned groups can include knownsubstituents such as: halogen (for example, chloro, fluoro, bromo, andiodo); alkoxy particularly those with 1 to 12 carbon atoms (for example,methoxy and ethoxy); substituted or unsubstituted alkyl groups,particularly lower alkyl groups (for example, methyl andtrifluoromethyl); alkenyl or thioalkyl (for example, methylthio andethylthio), particularly either of those with 1 to 12 carbon atoms;substituted and unsubstituted aryl, particularly those having from 6 to20 carbon atoms in the aromatic ring (for example, phenyl); andsubstituted or unsubstituted heteroaryl, particularly those having a 5-or 6-membered ring containing 1 to 3 heteroatoms selected from N, O, Sor Se (for example, pyridyl, thienyl, furyl, pyrrolyl, and theircorresponding benzo and naptho analogs); and other substituents thatwould be readily apparent in the art. Alkyl substituents particularlycontain 1 to 12 carbon atoms and specifically include “lower alkyl” thatis having from 1 to 6 carbon atoms, for example, methyl, ethyl, andt-butyl. Further, with regard to any alkyl group, alkylene group oralkenyl group, it will be understood that these can be branched orunbranched and include ring (cyclic) structures.

Uses

The non-aqueous metal catalytic compositions can be used for a varietyof purposes where efficient photocuring or photopolymerization is neededin various articles or devices. Such non-aqueous metal catalyticcompositions are sensitive to a chosen radiation wavelength as notedabove. For example, the non-aqueous metal catalytic compositions can beused to provide electrically-conductive metal patterns, for exampleusing electroless plating procedures that can be incorporated intovarious devices including but not limited to touch screen or othertransparent display devices that can be used in numerous industrial andcommercial products.

For example, touch screen technology can comprise different touch sensorconfigurations including capacitive and resistive touch sensors.Resistive touch sensors comprise several layers that face each otherwith a gap between adjacent layers that may be preserved by spacersformed during manufacturing. A resistive touch screen panel can compriseseveral layers including two thin, metallic, electrically-conductivelayers separated by a gap that can be created by spacers. When an objectsuch as a stylus, palm, or fingertip presses down on a point on thepanel's outer surface, the two metallic layers come into contact and aconnection is formed that causes a change in the electrical current.This touch event is sent to a controller for further processing.

Capacitive touch sensors can be used in electronic devices withtouch-sensitive features. These electronic devices can include but arenot limited to, televisions, monitors, and projectors that can beadapted to display images including text, graphics, video images,movies, still images, and presentations. The image devices that can beused for these display devices that can include cathode ray tubes(CRS's), projectors, flat panel liquid crystal displays (LCD's), LEDsystems, OLED systems, plasma systems, electroluminescent displays(ECD's), and field emission displays (FED's). For example, the presentinvention can be used to prepare capacitive touch sensors that can beincorporated into electronic devices with touch-sensitive features toprovide computing devices, computer displays, portable media playersincluding e-readers, mobile telephones and other communicating devices.

Systems and methods of fabricating flexible and optically complianttouch sensors in a high-volume roll-to-roll manufacturing process wheremicro electrically-conductive features can be created in a single passare possible using the present invention. The non-aqueous metalcatalytic compositions can be used in such systems and methods byapplication with printing members such as flexographic printing plates.Multiple patterns of non-aqueous metal catalytic compositions can beprinted on one or both sides of a substrate as described in more detailsbelow. For example, one predetermined pattern can be printed on one sideof the substrate and a different predetermined pattern can be printed onthe opposing side of the substrate. The printed patterns of thenon-aqueous metal catalytic compositions can then be further processedto provide electrically-conductive metal patterns such as for exampleusing electroless metal plating.

Non-Aqueous Metal Catalytic Compositions

In general, the non-aqueous metal catalytic compositions describedherein are sensitive throughout the UV to visible spectral region asdescribed above and are photocurable without appreciable application ofheat. Thus, photocuring can occur at essentially room temperature (forexample, as low as 18° C.) when all of the components of the non-aqueousmetal catalytic compositions are properly mixed together. Thenon-aqueous metal catalytic compositions are designed to be effectivewhen they comprise the essential components (a) through (f) describedherein, which are the only components necessary to achieve the desiredefficient photocuring. Optional addenda can also be included asdescribed below.

The non-aqueous metal catalytic composition useful in this inventioncomprises essential components (a) through (f) and any optionalcomponents as described below in the described amounts.

The essential component (a) is a silver complex comprising reduciblesilver ions, which complexes can be comprised of any suitable organic orinorganic moiety (or combination of moieties). Such silver complexes canbe mononuclear, dinuclear, trinuclear, or higher. The silver complexgenerally has a net neutral charge.

Some particularly useful silver complexes include but are not limitedto, silver nitrate, silver acetate, silver benzoate, silver nitrite,silver oxide, silver sulfate, silver thiocyanate, silver carbonate,silver myristate, silver citrate, silver phenylacetate, silver malonate,silver succinate, silver adipate, silver phosphate, silver perchlorate,silver tetrafluoroborate, silver acetylacetonate, silver lactate, silveroxalate, silver 2-phenylpyridine, and derivatives thereof. Other usefulsilver complexes include silver fluoride complexes such as silver (I)fluorosulfate, silver (I) trifluoroacetate, silver (I) trifluoromethanesulfate, silver (I) pentafluoropropionate, and silver (I)heptafluorobutyrate; β-carbonyl ketone silver (I) complexes; and silverproteins.

Useful silver complexes can be readily prepared using known proceduresand some can be purchased from commercial sources.

The noted silver complex (or combination thereof) is generally presentin the non-aqueous metal catalytic composition in an amount of at least2 weight %, and more typically in an amount of at least 2 weight % andup to and including 90 weight %, or even at least 10 weight % and up toand including 25 weight %, all based on the total essential components(a) through (f) in the non-aqueous metal catalytic composition.

A second essential component (b) is an organic phosphite or mixturethereof. Useful organic phosphites can be represented by the followingformula:(R′O)₃Pwherein the multiple R′ groups are the same or different substituted orunsubstituted alkyl groups having 1 to 20 carbon atoms or substituted orunsubstituted aryl groups having 6 or 10 carbon atoms in the aromaticrings, or two or three R′ groups can form a substituted or unsubstitutedcyclic aliphatic ring or fused ring system having up to and including 20carbon or heteroatoms in the rings. The alkyl groups described for R′can be interrupted with oxy groups or they can be substituted with oneor more hydroxy groups.

For example, representative organic phosphite include trimethylphosphite, triethyl phosphite, tri-iso-propyl phosphite, tri n-butylphosphite, tri-iso-propyl phosphite, tri-iso-butyl phosphite, triamylphosphite, tri-n-hexyl phosphite, tri-n-octyl phosphite, tri-n-nonylphosphite, tri(ethylene glycol) phosphite, tri(propylene glycol)phosphite, tri(iso-propylene glycol) phosphite, tri(n-butylene glycol)phosphite, tri(iso-butylene glycol) phosphite, tri(n-pentylene glycol)phosphite, tri(n-hexylene glycol) phosphite, tri(n-nonylene glycol)phosphite, tri(diethylene glycol) phosphite, tri(triethylene glycol)phosphite, tri(polyethylene glycol) phosphite, tri(polypropylene glycol)phosphite, or tri(polybutylene glycol) phosphite, and mixtures thereof.Similar compounds to those listed herein would be readily apparent toone skilled in the art, including various isomers or analogs of thosenamed.

The one or more organic phosphites are present in the non-aqueous metalcatalytic composition in an amount of at least 2 weight % and up to andincluding 10 weight %, or typically at least 2 weight % and up to andincluding 8 weight %, all based on the total amount of essentialcomponents (a) through (t) in the non-aqueous metal catalyticcomposition.

The non-aqueous metal catalytic composition also comprises an oxyaziniumsalt silver ion photoreducing agent as a third essential component (c).Such compounds are present in order to reduce the reducible silver ionsthat are present in the silver complex described above.

The useful oxyazinium salts are N-oxy-N-heterocyclic compounds having aheterocyclic nucleus (for example, N-oxyazinium salts), such as apyridinium, diazinium, or triazinium nucleus, or other similar nucleithat would be readily apparent to one skilled in the art. The oxyaziniumsalt can include one or more aromatic rings, typically carbocyclicaromatic rings, fused with the N-oxy-N-heterocyclic compound, includingquinolinium, isoquinolinium, benzodiazinium, phenanthridium, andnaphthodiazinium. Any convenient charge balancing counter-ion can beemployed to complete the oxyazinium salt photoinitiators, such ashalide, fluoroborate, hexafluoro-phosphate, toluene sulfonate, andothers that would be readily apparent to one skilled in the art. The oxygroup (—O—R₁) within the oxyazinium salt which quaternizes the ringnitrogen atom of the azinium nucleus can be selected from among avariety of synthetically convenient oxy groups. The oxyazinium salt canalso be an oligomeric or polymeric compound.

The oxyazinium salt can have a reduction potential less negative than−1.4 V and comprise an N-oxy group that is capable of releasing an oxyradical during irradiation of the non-aqueous metal catalyticcomposition.

Representative oxyazinium salt silver ion photoreducing agents can berepresented by the following Structure (I):

wherein A and B in Structure (I) independently represent a carbon, C—R₅,C—R₆, or nitrogen, and X is oxygen (O).

R₁, R₂, R₃, R₄, R₅, and R₆ are independently hydrogen, or substituted orunsubstituted alkyl groups having 1 to 12 carbon atoms or substituted orunsubstituted aryl groups having 6 or 10 carbon atoms in the carbocyclicring, which groups can be substituted with one or more acyloxy, alkoxy,aryloxy, alkylthio, arylthio, alkylsulfonyl, thiocyano, cyano, halogen,aikoxycarbonyl, aryloxycarbonyl, acetal, aroyl, alkylaminocarbonyl,arylaminocarbonyl, alkylaminocarbonyloxy, arylaminocarbonyloxy,acylamino, amino, alkylamino, arylamino, carboxy, sulfo, trihalomethyl,alkyl, aryl, heteroaryl, alkylureido, arylureido, succinimido,phthalimido groups, —CO—R₇ wherein R₇ is a substituted or unsubstitutedalkyl or a substituted or unsubstituted aryl group, or —(CH═CH)_(m)—R₈wherein R₅ is a substituted or unsubstituted aryl group or a substitutedor unsubstituted heterocyclic group.

Any of the A, B, and noted R groups in Structure (I), where chemicallyfeasible, can be joined together to form a ring. Y⁻ is a suitable chargebalancing anion that can be a separate charged moiety or a charged partof an A, B, or R group.

Other useful oxyazinium salts are represented by the following Structure(II):

wherein A in Structure (II) represents carbon, C—R₅, nitrogen, sulfur,or oxygen with sufficient bonds and substituents to form aheteroaromatic ring, and X is oxygen (O). R₁, R₂, R₃, R₄, and R₅ areindependently hydrogen, or substituted or unsubstituted alkyl or arylgroups as described above for Structure (I), or any two R groups can bejoined together to form a ring. Y⁻ is a charge balancing anion that canbe a separate charged moiety or part of a charged R group.

In some embodiments of Structures (I) and (II), R₁ is a substituted orunsubstituted alkyl group having 1 to 18 carbon atoms or a substitutedor unsubstituted aryl group having 6 or 10 carbon atoms in the aromaticring.

Other useful N-oxyazinium salt photoinitiators having a cation can berepresented by the following formulae:

wherein R₁ represents a substituted or unsubstituted alkyl group,substituted or unsubstituted aryl group, or an acyl group, as describedabove, and wherein R₁ can also include a charge balancing anion, the R₂groups independently represent hydrogen, or substituted or unsubstitutedalkyl, substituted or unsubstituted aryl, substituted or unsubstitutedalkoxy, or substituted or unsubstituted heteroaryl groups. The R₂ groupscan also be nitrile groups. X is a divalent linking group and Z is asubstituted or unsubstituted aliphatic linking group having 1 to 12atoms in the linking chain.

Other useful N-oxyazinium salt photoinitiators are illustrated byStructures III and IV and the compounds shown in TABLES 1 and 2 of U.S.Pat. No. 7,632,879 (Majumdar et al.) the disclosure of which isincorporated herein by reference for the teaching of these compounds.

Particularly useful oxyazinium salt silver ion photoreducing agents arecompounds OZ-1 through OZ-16 identified below in TABLE I.

TABLE I OZ-1

OZ-2

OZ-3

OZ-4

OZ-5

OZ-6

OZ-7

OZ-8

OZ-9

OZ-10

OZ-11

OZ-12

OZ-13

OZ-14

OZ-15

OZ-16

Mixtures of oxyazinium salts can be used if desired, and the totalamount of oxyazinium salt silver ion photoreducing agents in thenon-aqueous metal catalytic compositions described herein invention isgenerally at least 2 weight % and up to and including 25 weight % or upto and including 10 weight % based on the total amount of essentialcomponents (a) through (f) in the non-aqueous metal catalyticcomposition.

Essential component (d) in the non-aqueous metal catalytic compositionis a hindered pyridine compound that is has substituent alkyl or arylgroups in the ortho positions of the pyridine ring. The alkylsubstituents can be substituted or unsubstituted and linear, branched orcyclic in structure and generally comprise 1 to 18 carbon atoms, and thearyl substituents can be substituted or unsubstituted phenyl or naphthylgroups. Such hindered pyridine compounds are generally weaker bases thanmeta- and para-substituted pyridine compounds [for example, see J. Org.Chem. 33, 1922 (1968)]. Useful examples of such compounds include butare not limited to, 2,6-dimethylpyridine, 2-t-butylpyridine,2-phenylpyridine, and other compounds that would be readily apparent toone skilled in the art, and 2,6-dimethylpyridine is particularly useful.

Such hindered pyridine compounds are present in the non-aqueous metalcatalytic composition in an amount of at least 5 weight % and up to andincluding 20 weight %, or particularly of at least 5 weight % and up toand including 10 weight %, all based on the total amount of essentialcomponents (a) through (f) in the non-aqueous metal catalyticcomposition.

In addition, the non-aqueous metal catalytic composition comprisesessential component (e) that comprises one or more photocurablecomponents, one or more non-curable polymers, or a combination of one ormore photocurable components and one or more non-curable polymers.

Overall, the one or more photocurable components, the one or morenon-curable polymers, or combination thereof can be present in thenon-aqueous metal catalytic composition in an amount of at least 10weight % and up to and including 88 weight %, and typically at least 10weight % and up to and including 50 weight %, all based on the totalamount of essential components (a) through (f) in the non-aqueous metalcatalytic composition. The amounts of each type of component (e) can beadjusted depending upon what the component is designed to do and usefulamounts of specific photocurable components and non-curable polymers aredescribed below. The amounts can also be adjusted when there aremultiple materials comprising the photocurable components, such asphotocurable monomers, oligomers, or polymers as well as any freeradical photoinitiators that may be needed with such materials.

The useful photocurable components are considered materials that canparticipate in a photocuring reaction, for example as a photocurablemonomer, oligomer, or polymer or as a photoinitiator or co-initiator.Such photocurable components can be designed to participate in eitherfree radical photocuring in which free radicals are generated uponphotoexposure, or in acid-catalyzed photocuring in which an acid isgenerated for reaction and curing of an epoxy compound.

In general, the photocurable components are sensitive throughout the UVto visible spectral region as described above and are photocurable orcause photocuring in these electromagnetic regions without appreciableapplication of heat. Thus, photocuring or photopolymerization can occurat essentially room temperature (for example, as low as 18° C.) when allof the components are properly mixed together.

Examples of photocurable components that participate in acid-catalyzedphotocuring including photopolymerizable epoxy materials that areorganic compounds having at least one oxirane ring that is polymerizableby a ring opening mechanism. Such epoxy materials, also called“epoxides”, include monomeric epoxy compounds and epoxides of thepolymeric type and can be aliphatic, cycloaliphatic, aromatic orheterocyclic. These materials generally have, on the average, at leastone polymerizable epoxy group per molecule, or typically at least about1.5 and even at least about 2 polymerizable epoxy groups per molecule.Polymeric epoxy materials include linear polymers having terminal epoxygroups (for example, a diglycidyl ether of a polyoxyalkylene glycol),polymers having skeletal (backbone) oxirane units (for example,polybutadiene polyepoxide), and polymers having pendant epoxy groups(for example, a glycidyl methacrylate polymer or copolymer).

The polymerizable epoxy materials can be single compounds or they can bemixtures of different epoxy materials containing one, two, or more epoxygroups per molecule. The “average” number of epoxy groups per moleculeis determined by dividing the total number of epoxy groups in the epoxymaterial by the total number of epoxy-containing molecules present.

The epoxy materials can vary from low molecular weight monomericmaterials to high molecular weight polymers and they can vary greatly inthe nature of the backbone and substituent (or pendant) groups. Forexample, the backbone can be of any type and substituent groups thereoncan be any group that does not substantially interfere with cationicphotocuring process desired at room temperature. Illustrative ofpermissible substituent groups include but are not limited to, halogens,ester groups, ethers, sulfonate groups, siloxane groups, nitro groups,and phosphate groups. The molecular weight of the epoxy materials can beat least 58 and up to and including 100,000, or even higher.

Specific useful epoxy materials would be readily apparent to one skilledin the art. Many commercially available epoxy materials are useful inthe present invention, glycidyl ethers such as bisphenol-A-diglycidylether (DGEBA), glycidyl ethers of bisphenol S and bisphenol F,butanediol diglycidyl ether, bisphenol-A-extended glycidyl ethers,phenol-formaldehyde glycidyl ethers (epoxy novolacs) andcresol-formaldehyde glycidyl ethers (epoxy cresol novolacs), epoxidizedalkenes such as 1,2-epoxyoctane, 1,2,13,14-tetradecane diepoxide,1,2,7,8-octane diepoxide, octadecylene oxide, epichlorohydrin, styreneoxide, vinyl cyclohexene oxicyclohexene oxide, glycidol, glycidylmethacrylate, diglycidyl ether of Bisphenol A (for example, thoseavailable under the EPON trademark such as EPON™ 828, EPON™ 825, EPON™1004, and EPON™ 1010 from Momentive, DER-331, DER-332, and DER-334resins from Dow Chemical Co.), vinyl cyclohexene dioxide (for example,ERL-4206 resin from Polyscience),3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexene carboxylate (for example,ERL-4221, UVR 6110, or UVR 6105 resin from Dow Chemical Company),3,4-epoxy-6-methylcyclohexylmethyl-3,4-epoxy-6-methyl-cyclohexenecarboxylate (from Pfalz and Bauer),bis(3,4-epoxy-6-methylcyclohexylmethyl) adipate,bis(2,3-epoxy-cyclopentyl) ether, aliphatic epoxy modified withpolypropylene glycol, dipentene dioxide, epoxidized polybutadiene (forexample, Oxiron 2001 resin from FMC Corp.), silicone resin containingepoxy functionality, flame retardant epoxy resins (for example, DER-580resin, a brominated bisphenol type epoxy resin available from DowChemical Co.), 1,4-butanediol diglycidyl ether of phenol formaldehydenovolak (for example, DEN-431 and DEN-438 resins from Dow Chemical Co.),resorcinol diglycidyl ether (for example, CYRACURE™ resin from DowCorning Corp.),2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy)cyclohexane-meta-dioxane,2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy)cyclohexane-meta-dioxane,vinyl cyclohexene monoxide, 1,2-epoxyhexadecane (for example, CYRACURE™resin from Dow Corning Corp.), alkyl glycidyl ethers such as HELOXY™Modifier 7 and HELOXY™ Modifier 8 (from Momentive), butyl glycidyl ether(for example, HELOXY™ Modifier 61 from Momentive), cresyl glycidyl ether(for example, HELOXY™ Modifier 62 from Momentive), p-tert butylphenylglycidyl ether (for example, HELOXY™ Modifier 65 from Momentive),polyfunctional glycidyl ethers such as diglycidyl ether of1,4-butanediol (for example, HELOXY™ Modifier 67 from Momentive),diglycidyl ether of neopentyl glycol (for example, HELOXY™ Modifier 68from Momentive), diglycidyl ether of cyclohexanedimethanol (for example,HELOXY™ Modifier 107 from Momentive), trimethylol ethane triglycidylether (for example, HELOXY™ Modifier 44 from Momentive), trimethylolpropane triglycidyl ether (for example, HELOXY™ Modifier 48 fromMomentive), polyglycidyl ether of an aliphatic polyol (for example,HELOXY™ Modifier 84 from Momentive), polyglycol diepoxide (for example,HELOXY™ Modifier 32 from Momentive), bisphenol F epoxides (for example,EPN-1138 or GY-281 resin from Huntman Advanced Materials), and9,9-bis>4-(2,3-epoxypropoxy)-phenyl fluorenone (for example, EPON™ 1079resin from Momentive).

Still other useful epoxy materials are resins such as copolymers derivedfrom acrylic acid esters reacted with glycidol such as glycidyl acrylateand glycidyl methacrylate, copolymerized with one or more ethylenicallyunsaturated polymerizable monomers. Examples of such copolymers arepoly(styrene-co-glycidyl methacrylate) (50:50 molar ratio), poly(methylmethacrylate-co-glycidyl acrylate) (50:50 molar ratio), and poly(methylmethacrylate-co-ethyl acrylate-co-glycidyl methacrylate) (62.5:24:13.5molar ratio).

One or more photopolymerizable epoxy materials can be included in thenon-aqueous metal catalytic composition in a suitable amount to providethe desired efficient photocuring or photopolymerization. For example,the one or more photopolymerizable epoxy materials can be present in anamount of at least 1.0 weight % and up to and including 50 weight %, allbased on the total amount of components (a) through (f) in thenon-aqueous metal catalytic composition.

Various compounds can be used to generate a suitable acid to participatein the photocuring of the photopolymerizable epoxy materials describedabove. Some of these “photoacid generators” are acidic in nature andothers are nonionic in nature. Other useful photoacid generators besidesthose described below would be readily apparent to one skilled in theart in view of the teaching provided herein. The various compoundsuseful as photoacid generators can be purchased from various commercialsources or prepared using known synthetic methods and startingmaterials.

Onium salt acid generators useful in the practice of this inventioninclude but are not limited to, salts of diazonium, phosphonium,iodonium, or sulfonium salts including polyaryl diazonium, phosphonium,iodonium, and sulfonium salts. The iodonium or sulfonium salts includebut not limited to, diaryliodonium and triarylsulfonium salts. Usefulcounter anions include but are not limited to complex metal halides,such as tetrafluoroborate, hexafluoroantimonate,trifluoromethanesulfonate, hexafluoroarsenate, hexafluorophosphate, andarenesulfonate. The onium salts can also be oligomeric or polymericcompounds having multiple onium salt moieties as well as moleculeshaving a single onium salt moiety.

Useful iodonium salts can be simple salts (for example, containing ananion such as chloride, bromide, iodide, or C₄H₅SO₃ ⁻) or a metalcomplex salt (for example, containing SbF₆ ⁻, PF₆ ⁻, BF₄ ⁻,tetrakis(perfluorophenyl)borate, or SbF₅OH₃₁AsF₆ ⁻). Mixtures of any ofthese iodonium salts of the same or different class can be used ifdesired.

The selection of a particular onium salt can be made for optimumproperties with the other essential components and amounts. Particularlyuseful sulfonium salts include but are not limited to,triaryl-substituted salts such as mixed triarylsulfoniumhexafluoroantimonates (for example, commercially available as UVI-6974from Dow Chemical Company), mixed triarylsulfonium hexafluorophosphates(for example, commercially available as UVI-6990 from Dow ChemicalCompany), and arylsulfonium hexafluorophosphates.

One or more onium salts (such as an iodonium salt or a sulfonium salt)are generally present in the non-aqueous metal catalytic composition inan amount of at least 0.05 weight % and up to and including 10 weight %,or typically at least 0.1 weight % and up to and including 10 weight %,or even at least 0.5 weight % and up to and including 5 weight %, allbased on the total amount of components (a) through (f) in thenon-aqueous metal catalytic composition.

Besides onium salts described above, nonionic photoacid generators canbe useful, which compounds include but are not limited to, diazomethanederivatives such as, glyoxime derivatives, bissulfone derivatives,disulfono derivatives, nitrobenzyl sulfonate derivatives, sulfonic acidester derivatives, and sulfonic acid esters of N-hydroxyimides. One ormore nonionic photoacid generators can be present in the non-aqueousmetal catalytic composition in an amount of at least 0.05 weight % andup to and including 10 weight %, or typically at least 0.1 weight % andup to and including 10 weight %, or even at least 0.5 weight % and up toand including 5 weight %, all based on the total amount of components(a) through (f) in the non-aqueous metal catalytic composition.

For free radical photocuring chemistry, the photocurable component canbe one or more free-radically polymerizable compounds to providefree-radically polymerizable functionality, including ethylenicallyunsaturated polymerizable monomers, oligomers, or polymers such asmono-functional or multi-functional acrylates (also includesmethacrylates). Such free-radically polymerizable compounds comprise atleast one ethylenically unsaturated polymerizable bond and they cancomprise two or more of these unsaturated moieties in many embodiments.Suitable materials of this type contain at least one ethylenicallyunsaturated polymerizable bond and are capable of undergoing addition(or free radical) polymerization. Such free radically polymerizablematerials include mono-, di-, or poly-acrylates and methacrylates,co-polymerizable mixtures of acrylate monomers and acrylate oligomers,and vinyl compounds such as styrene and styrene derivatives, diallylphthalate, divinyl succinate, divinyl adipate, and divinyl phthalate.Mixtures of two or more of these free radically polymerizable materialscan be used if desired. Such materials can be purchased from a number ofcommercial sources or prepared using known synthetic methods andstarting materials.

The one or more free radically polymerizable materials can be present inthe non-aqueous metal catalytic compositions in an amount of at least 20weight % and up to and including 60 weight %, based on the total amountof components (a) through (f) in the non-aqueous metal catalyticcomposition.

The photocurable component can also include one or more free radicalphotoinitiators that are also present in the photopolymerizablecompositions to generate free radicals in the presence of thefree-radically polymerizable compounds. Such free radicalphotoinitiators include any compound that is capable of generating freeradicals upon exposure to photocuring radiation used in the practice ofthis invention such as ultraviolet or visible radiation. For example,free radical photoinitiators can be selected from triazine compounds,thioxantone compounds, benzoin compounds, carbazole compounds, diketonecompounds, sulfonium borate compounds, diazo compounds, and biimidazolecompounds, benzophenone compounds, anthraquinone compounds, acetophenonecompounds, and others that would be readily apparent to one skilled inthe art. Mixtures of such compounds can be selected from the same ordifferent classes. Many of such free radical photoinitiators can beobtained from various commercial sources.

Such free radical photoinitiators can be present in the non-aqueousmetal catalytic composition in an amount of at least 0.1 weight % and upto and including 10 weight %, or typically at least 1 weight % and up toand including 5 weight %, all based on the total amount of components(a) through (f) in the non-aqueous metal catalytic composition.

Essential component (e) can be a non-curable polymer that acts as abinder material or if in liquid form, an organic solvent for thenon-aqueous metal catalytic composition. Examples of such polymersinclude but are not limited to polyalkyl methacrylates, poly(vinylacetate), polystyrene, polyvinyl alcohol), polypropylene, poly(vinylbutyral) (for example, BUTVAR™ resin) and other polyvinyl acetals, andother polymers that would be readily apparent to one skilled in the artfrom this teaching. Useful polymers also include copolymers derived atleast in part from vinyl alcohol or derivatives thereof.

Useful photosensitizers as essential component (f) can be present in thenon-aqueous metal catalytic compositions, and such compounds aredifferent from all of the other components in the non-aqueous metalcatalytic composition.

For example, for the acid catalyzed chemistry, an electron donorphotosensitizer can be present. Useful electron donor photosensitizersshould be soluble in the non-aqueous metal catalytic composition, freeof functionalities that would substantially interfere with thephotocuring process, and capable of light absorption (sensitivity)within the range of exposure wavelengths.

For example, each of the electron donor photosensitizers generally hasan oxidation potential of at least 0.4 V and up to and including 3 V vs.SCE, or more typically of at least 0.8 V and up to and including 2 V vs.SCE.

In general, many different classes of compounds can be used as electrondonor photosensitizers including but are not limited to, aromatics suchas naphthalene, 1-methylnaphthalene, anthracene,9,10-dimethoxyanthracene, benz[a]anthracene, pyrene, phenanthrene,benzo[c]phenanthrene, and fluoranthene; thioxanthones and xanthones;ketones including aromatic ketones such as fluorenone, and coumarin dyessuch as ketocoumarins such as those with strong electron donatingmoieties (such as dialkylamino). Other suitable electron donorphotosensitizers include xanthene dyes, acridine dyes, thiazole dyes,thiazine dyes, oxazine dyes, azine dyes, aminoketone dyes, porphyrins,aromatic polycyclic hydrocarbons, p-substituted aminostyryl ketonecompounds, aminotriarylmethanes, merocyanines, squarylium dyes, andpyridinium dyes.

In some embodiments, the electron donor photosensitizer is a pyrene,benzopyrene, perylene, or benzoperylene.

In other embodiments, useful photosensitizers include but are notlimited to, ketocoumarins, xanthones, thioxanthones, arylketones, andpolycyclic aromatic hydrocarbons in amounts described above.

The one or more electron donor photosensitizers can be present in thenon-aqueous metal catalytic composition in an amount of at least 1weight % and up to and including 5 weight %, and typically at least 1weight % and up to and including 4 weight %, based on the total amountof essential components (a) through (f) in the non-aqueous metalcatalytic composition.

The non-aqueous metal catalytic compositions are generally prepared forcoating, printing, or other means of application by simply admixing,under “safe light” conditions, the essential components (a) through (f)and any optional components described herein. Such materials can bemixed and dispersed within suitable inert organic solvents to provide aninert organic solvent medium, which inert organic solvents do not reactappreciably with any other components incorporated therein. Examples ofsuitable inert organic solvents include but are not limited to, acetone,dichloromethane, isopropanol, DOWANO® PM solvent, ethylene glycol, andmixtures thereof. When one or more essential components (a) through (f)are in liquid form, those components can act as the “solvent” for thenon-aqueous metal catalytic composition, or used in combination with oneor more inert organic solvents. Inert organic solvent-free non-aqueousmetal catalytic compositions can be prepared by simply dissolving,dispersing, and mixing the essential components (a) through (f) and anyoptional components with or without the use of mild heating tofacilitate dissolution or dispersion.

When inert organic solvents are used, they can be present in thenon-aqueous metal catalytic composition an amount of at least 1 weight %and up to and including 70 weight % or at least 20 weight % and up toand including 50 weight %, based on the total weight of the non-aqueousmetal catalytic composition. The amount of inert organic solvents can bejudiciously chosen depending upon the particular materials used, themeans for applying the resulting non-aqueous metal catalyticcomposition, and desired properties including composition uniformity.

In some embodiments one or more of the photocurable components ornon-curable polymers acts as an organic solvent medium and no additionalinert organic solvents are purposely added to the non-aqueous metalcatalytic composition.

The non-aqueous metal catalytic composition can further include carbonblack, graphite, graphene, carbon nanotubes, or other sources of carbonif desired in an amount of at least 0.5 weight % based on the totalweight of the essential components (a) through (f) described above.

It is also possible to include carbon-coated metal particles such ascarbon-coated copper particles or carbon-coated silver particles indesirable amounts.

In some embodiments of this invention, the non-aqueous metal catalyticcomposition comprises:

-   -   (a) the silver complex comprising reducible silver ions, in an        amount of at least 2 weight % and up to and including 90 weight        %,    -   (b) the organic phosphite in an amount of at least 2 weight %        and up to and including 10 weight %,    -   (c) the oxyazinium salt silver ion photoreducing agent in an        amount of at least 2 weight % and up to and including 10 weight        %,    -   (d) the hindered pyridine in an amount of at least 5 weight %        and up to and including 20 weight %,    -   (e) the photocurable component, non-curable polymer, or a        combination of a photocurable component and a non-curable        polymer, in an amount of at least 10 weight % and up to and        including 88 weight %, and    -   (f) the photosensitizer is present in an amount of at least 1        weight % and up to and including 10 weight %,    -   all amounts based on the total amount of components (a)        through (f) in the non-aqueous metal catalytic composition.

Such non-aqueous metal catalytic compositions can also further compriseone or more inert organic solvents to provide an inert organic solventmedium.

Preparing Non-aqueous Metal Catalytic Compositions

The essential components (a) through (f) described above and anyoptional components, with or without one or more inert organic solventscan be blended to prepare a non-aqueous metal catalytic compositionunder “safe light” conditions if desired. This mixing can occur insuitable inert organic solvents (as described above) if desired. Theresulting non-aqueous metal catalytic composition can be provided inliquid form having a viscosity of at least 1 centipoise and up to andincluding 100,000 centipoises at 25° C., or it can be provided as a freeflowing powder. The non-aqueous metal catalytic composition can beapplied to a variety of substrates (described above) by conventionalmeans and photocured to the tack-free state within 1 second or up to 10minutes or more.

Examples of suitable inert organic solvents include but are not limitedto, acetone, methanol, ethanol, isopropanol, 1-methoxy-2-propanol,methylene chloride, and any other inert organic solvent that does notreact appreciably with any of the components of the non-aqueous metalcatalytic compositions. Mixtures of inert organic solvents can also beused.

Alternatively, a photocurable component can be used as the solvent formixing of the essential and any optional components, or such a liquidmaterial can be used in combination with inert organic liquid(s). Aninert organic solvent can be used also to aid in obtaining a liquidformulation with suitable viscosity for desired methods of applicationto a substrate such as various coating methods, ink jet inks, or othermaterials or operations, such as for printing with relief elements orflexographic printing plates. However, organic solvent-free non-aqueousmetal catalytic compositions also can be prepared by simply dissolvingor dispersing the essential and optional components in one of thecomponents that is in liquid form, with or without mild heating.

The amounts of the various components for these formulations aredescribed above for the non-aqueous metal catalytic compositions.

Photoreducing can be achieved by activating (irradiating) thenon-aqueous metal catalytic composition to reduce the reducible silverions and also optionally, to cause polymerization or curing of one ormore photocurable components, for example in the presence of oxygen.This photoreduction can be achieved by exposure to radiant energy suchas ultraviolet light as described above. Desirable photoreduction isdesirably achieved using UV or visible irradiation having a wavelengthof at least 150 nm to and including 700 nm and at intensity of at least1 mJ/cm² and up to and including 1000 mJ/cm² or more typically of atleast 1 mJ/cm² and up to and including 800 mJ/cm². More details of thisprocess are provided below.

Use of Non-aqueous Metal Catalytic Compositions

As noted above, the non-aqueous metal catalytic composition can beformed in a suitable manner (uniformly or patternwise) on one or moresupporting sides of a suitable substrate to provide a precursor articlecomprising a metal catalytic layer or a metal catalytic pattern.

The non-aqueous metal catalytic composition can be photocured orphotopolymerized using suitable radiation as described above includingultraviolet light or visible actinic light, or both to photoreduce thereducible silver ions to silver particles in a fashion corresponding tothe formed metal catalytic layer or metal catalytic pattern. One or moresuitable light sources can be used for the exposure process. Eachprecursor article can be exposed individually as a single element, or inalternative embodiments described below, a web (for example, aroll-to-roll continuous web) of multiple precursor articles in multipleportions of a continuous web of substrate can be exposed as the web ispassed through exposure stations, or the exposure device is passed overthe web. The same or different non-aqueous metal catalytic compositionscan be applied (for example, printed) on both supporting sides of thesubstrate whether it is in the form of a single element or continuousweb. In many embodiments, different conductive metal patterns can beformed on opposing supporting sides of the substrate (or continuousweb).

More specifically, the non-aqueous metal catalytic composition can beapplied in a uniform or pattern-wise manner to any suitable substrateusing any means for application, such as dip coating, roll coating,hopper coating, spray coating, spin coating, ink jetting,photolithographic imprinting, “flexographic” printing using printingelements including flexographic printing members (such as flexographicprinting plates and flexographic printing sleeves), lithographicprinting using lithographic printing plates, and gravure or intaglioprinting using appropriate printing members.

When the non-aqueous metal catalytic composition is uniformly applied toa suitable substrate, it can be “imaged” or selectively exposed (orpatterned) with exposing radiation through a suitable photomask (maskingelement) having the desired pattern, to reduce the silver ions to silverparticles (metal) in a corresponding imagewise fashion. Excessnon-aqueous metal catalytic composition can be then appropriatelyremoved using a suitable “developer” organic solvent medium. Thesefeatures or steps can be carried out on both (opposing) supporting sidesof the substrate.

Suitable substrates (also known as “receiver elements”) can be composedof any suitable material as long as it does not inhibit the purpose ofthe non-aqueous metal catalytic composition. For example, substrates canbe formed from materials including but are not limited to, polymericfilms, metals, glasses (untreated or treated for example withtetrafluorocarbon plasma, hydrophobic fluorine, or a siloxanewater-repellant material), silicon or ceramic wafers, fabrics, papers,and combinations thereof (such as laminates of various films, orlaminates of papers and films) provided that a uniform layer or patternof a non-aqueous metal catalytic composition can be formed thereon in asuitable manner and followed by irradiation on at least one supportivesurface thereof. The substrate can be transparent or opaque, and rigidor flexible. The substrate can include one or more auxiliary polymericor non-polymeric layers or one or more patterns of other materialsbefore the non-aqueous metal catalytic composition is applied accordingto the present invention.

A supportive surface of the substrate can be treated for example with aprimer layer or electrical or mechanical treatments (such as graining)to render that surface “receptive” to improve adhesion of thenon-aqueous metal catalytic composition and resulting photocured metalcatalytic layer or metal catalytic pattern. An adhesive layer can bedisposed on the substrate and this adhesive layer can have variousproperties in response to stimuli (for example, it can be thermallyactivated, solvent activated, or chemically activated) and that servesto provide a receptive layer. Useful adhesive materials of this type aredescribed for example in [0057] of U.S. Patent Application 2008/0233280(Blanchet et al.).

In some embodiments, the substrate comprises a separate receptive layeras a receptive surface disposed on the supportive side of the substrate,which receptive layer and substrate can be composed of a material suchas a suitable polymeric material that is highly receptive of thenon-aqueous metal catalytic composition. Such receptive layer can haveany suitable dry thickness of at least 0.05 μm when measured at 25° C.

The supportive sides of the substrate, especially polymeric substrates,can be treated by exposure to corona discharge, mechanical abrasion,flame treatments, or oxygen plasmas, or by coating with variouspolymeric films, such as poly(vinylidene chloride) or an aromaticpolysiloxane as described for example in U.S. Pat. No. 5,492,730 (Balabaet al.) and U.S. Pat. No. 5,527,562 (Balaba et al.) and U.S. PatentApplication Publication 2009/0076217 (Gommans et al.).

Suitable substrate materials for forming precursor articles of thepresent invention include but are not limited to, metallic films orfoils, metallic films on polymer, glass, or ceramic supports, metallicfilms on electrically conductive film supports, semi-conducting organicor inorganic films, organic or inorganic dielectric films, or laminatesof two or more layers of such materials. For example, useful substratescan include polymeric films such as poly(ethylene terephthalate) films,poly(ethylene naphthalate) films, polyimide films, polycarbonate films,polyacrylate films, polystyrene films, polyolefin films, and polyimidefilms, silicon and other ceramics, metal foils such as aluminum foils,cellulosic papers or resin-coated or glass-coated papers, glass orglass-containing composites, metals such as aluminum, tin, and copper,and metalized films. The substrate can also include one or more chargeinjection layers, charge transporting layers, and semi-conducting layerson which the non-aqueous metal catalytic composition pattern is formed.

Particularly useful substrates are polyesters films such as films ofpoly(ethylene terephthalate), polycarbonate, or poly(vinylidenechloride) films with or without surface-treatments as noted above, orcoatings.

Useful substrates can have a desired dry thickness depending upon theeventual use of the article formed therefrom, for example itsincorporation into various articles or optical or display devices. Forexample, the substrate dry thickness (including all treatments andauxiliary layers) can be at least 0.001 mm and up to and including 10mm, and especially for polymeric films, the substrate dry thickness canbe at least 0.008 mm and up to and including 0.2 mm.

The substrate used to prepare the articles described herein can beprovided in various forms, such as for example, individual sheets in anysize or shape, and continuous webs such as continuous webs oftransparent substrates including transparent polyester substrates thatare suitable for roll-to-roll operations. Such continuous webs can bedivided or formed into individual first, second, and additional portionson one or both supportive sides that can be used to form the same ordifferent photoreduced patterns from the same or different non-aqueousmetal catalytic compositions.

After application of the non-aqueous metal catalytic composition, anyinert organic solvents can be removed by drying or a pre-bakingprocedure that does not adversely affect the remaining components orprematurely cause curing. Useful drying conditions can be as low as roomtemperature for as little as 5 seconds and up to and including severalhours depending upon the manufacturing process. In most processes, suchas roll-to-roll processes described below, the drying conditions can beat high enough temperatures to remove at least 90% of the inert organicsolvent within at least 1 second.

Any formed uniform metal catalytic layer can have a dry thickness of atleast 0.1 μm and up to and including 10 μm, or typically at least 0.2 μmand up to and including 1 μm, and the optimal dry thickness can betailored for the intended use of the resulting uniform photoreducedlayer, which generally has about the same dry thickness as the uniformlayer of the non-photoreduced non-aqueous metal catalytic composition.Such a uniform metal catalytic layer can be applied to both (opposing)supporting sides of the substrate, which uniform layers can have thesame or different non-aqueous metal catalytic compositions or drythickness.

Any applied pattern of the non-aqueous metal catalytic composition cancomprise a grid of lines (or other shapes including circles or anirregular network) having an average thickness (or width) of at least0.2 μm and up to and including 100 μm, or typically of at least 5 μm andup to and including 10 μm, and the optimal dry thickness (or width) canbe tailored for the intended use of the resulting uniform photoreducedlayer, which generally has about the same dry thickness (or width) asthe grid lines of the non-photoreduced non-aqueous metal catalyticcomposition.

Thus, the present invention provides precursor articles comprising asubstrate and uniform layers or patterns of the non-aqueous metalcatalytic composition, wherein such precursor articles can be thenappropriate exposed (for example as described above at a wavelength ofat least 150 nm and up to and including 700 nm) to reduce silver ions tosilver particles, for example in the presence of oxygen, to provideintermediate articles with metal catalytic layers or metal catalyticpatterns.

For example, the photoreducing of the reducible silver ions to silvercan provide particles having an average particle size of at least 10 nmand up to and including 1000 nm (or at least 20 nm and up to andincluding 500 nm) and at least 80% (or at least 90%) of the number ofthe silver particles have a particle size of at least 10 nm and up toand including 100 nm.

During exposure to reduce the silver ions, photocuring can be initiatedwith any photocurable components present in the metal catalytic layer ormetal catalytic pattern, and the resulting silver particles can besurrounded in a photocured matrix derived from a photocurable componentand other remaining components.

In some embodiments, the same or different non-aqueous metal catalyticcomposition can be applied in a suitable manner on both supporting sides(main surfaces) of the substrate to form “duplex” or dual-sidedprecursor articles, and each applied non-aqueous metal catalyticcomposition can be in the form of the same or different uniform metalcatalytic layer or metal catalytic pattern.

In many embodiments, a metal catalytic pattern of the non-aqueous metalcatalytic composition is applied on one or both (opposing) supportingsides of the substrate (for example as a roll-to-roll web) using arelief element such as elastomeric relief elements derived fromflexographic printing plate precursors, many of which are known in theart and some are commercially available, for example as the CYREL®Flexographic Photopolymer Plates from DuPont and the Flexcel SR and NXFlexographic plates from Eastman Kodak Company.

Particularly useful elastomeric relief elements are derived fromflexographic printing plate precursors and flexographic printing sleeveprecursors, each of which can be appropriately imaged (and processed ifneeded) to provide the relief elements for “printing” or applying asuitable metal catalytic pattern.

For example, useful elastomeric relief elements can be comprised of oneor more elastomeric layers, with or without a substrate, in which arelief image can be generated using suitable imaging means.

For example, the elastomeric relief element (for example, flexographicprinting member) having a relief layer comprising an uppermost reliefsurface and an average relief image depth (pattern height) of at least50 μm, or typically having an average relief image depth of at least 100μm relative from the uppermost relief surface, can be prepared fromimagewise exposure of an elastomeric photopolymerizable layer in anelastomeric relief element precursor such as a flexographic printingmember precursor, for example as described in U.S. Pat. No. 7,799,504(Zwadlo et al.) and U.S. Pat. No. 8,142,987 (Ali et al.) and U.S. PatentApplication Publication 2012/0237871 (Zwadlo), the disclosures of all ofwhich are incorporated herein by reference for details of suchflexographic printing member precursors. Such elastomericphotopolymerizable layers can be imaged through a suitable mask image toprovide an elastomeric relief element (for example, flexographicprinting plate or flexographic printing sleeve). In some embodiments,the relief layer comprising the relief pattern can be disposed on asuitable substrate. Other useful materials and image formation methods(including development) for provide elastomeric relief images are alsodescribed in the noted Ali et al. patent. The relief layer can bedifferent if different patterns of non-aqueous metal catalyticcompositions are applied to opposing supporting sides of the substrate.

In other embodiments, the elastomeric relief element is provided from adirect (or ablation) laser-engraveable elastomer relief elementprecursor, with or without integral masks, as described for example inU.S. Pat. No. 5,719,009 (Fan), U.S. Pat. No. 5,798,202 (Cushner et al.),U.S. Pat. No. 5,804,353 (Cushner et al.), U.S. Pat. No. 6,090,529(Gelbart), U.S. Pat. No. 6,159,659 (Gelbart), U.S. Pat. No. 6,511,784(Hiller et al.), U.S. Pat. No. 7,811,744 (Figov), U.S. Pat. No.7,947,426 (Figov et al.), U.S. Pat. No. 8,114,572 (Landry-Coltrain etal.), U.S. Pat. No. 8,153,347 (Veres et al.), U.S. Pat. No. 8,187,793(Regan et al.), and U.S. Patent Application Publications 2002/0136969(Hiller et al.), 2003/0129530 (Leinenback et al.), 2003/0136285 (Telseret al.), 2003/0180636 (Kanga et al.), and 2012/0240802 (Landry-Coltrainet al.), the disclosures of all of which are incorporated herein fordetails of such laser-engraveable precursors.

When the noted elastomeric relief elements are used in the presentinvention, the non-aqueous metal catalytic composition can applied in asuitable manner to the uppermost relief surface (raised surface) in theelastomeric relief element. Application to a substrate can beaccomplished in a suitable procedure and it is desirable that as littleas possible is coated onto the sides (slopes) or recesses of the reliefdepressions. Anilox roller systems or other roller application systems,especially low volume Anilox rollers, below 2.5 billion cubicmicrometers per square inch (6.35 billion cubic micrometers per squarecentimeter) and associated skive knives can be used. Optimum metering ofthe non-aqueous metal catalytic composition onto the uppermost reliefsurface can be achieved by controlling viscosity or thickness, orchoosing an appropriate application means.

For example, the non-aqueous metal catalytic composition can have aviscosity during this application of at least 1 cps (centipoise) and upto and including 5000 cps, or at least 1 cps to and up to and including1500 cps. The thickness of the non-aqueous metal catalytic compositionon the relief image is generally limited to a sufficient amount that canreadily be transferred to a substrate but not too much to flow over theedges of the elastomeric relief element in the recesses duringapplication.

The non-aqueous metal catalytic composition can be fed from an Anilox orother roller inking system in a measured amount for each printedprecursor article. In one embodiment, a first roller can be used totransfer the non-aqueous metal catalytic composition from an “ink” panor a metering system to a meter roller or Anilox roller. The non-aqueousmetal catalytic composition is generally metered to a uniform thicknesswhen it is transferred from the Anilox roller to a printing platecylinder. When the substrate is moved through the roll-to-roll handlingsystem from the printing plate cylinder to an impression cylinder, theimpression cylinder applies pressure to the printing plate cylinder thattransfers an image from an elastomeric relief element to the substrate.

After the non-aqueous metal catalytic composition has been applied tothe uppermost relief surface (or raised surface) of the elastomericrelief element, it can be useful to remove at least 25 weight % of anyinert organic solvents included therein to form a viscous deposit on theuppermost relief surface of the relief image. This removal of inertorganic solvents can be achieved in any manner, for example using jetsof hot air, evaporation at room temperature, or heating in an oven at anelevated temperature, or other means known in the art for removing asolvent.

Once on the substrate, either in a uniform metal catalytic layer orpredetermined metal catalytic pattern of grid lines or other shapes (onone or opposing supporting sides of the substrate), the non-aqueousmetal catalytic composition in the precursor article can be irradiatedwith suitable radiation as described above from a suitable source suchas a fluorescent lamp or LED to provide a silver metal-containing andphotocured metal catalytic layer or a silver metal-containing photocuredmetal catalytic pattern on the substrate. For example, silver ionreduction and any photocuring can be achieved by the use of UV-visibleirradiation having a wavelength (λ_(max)) of at least 150 nm and up toand including 700 nm and at intensity of at least 1,000 microwatts/cm²and up to and including 80,000 microwatts/cm². The irradiation systemused to generate such radiation can consist of one or more ultravioletlamps for example in the form of 1 to 50 discharge lamps, for example,xenon, metallic halide, metallic arc (such as a low, medium or highpressure mercury vapor discharge lamps having the desired operatingpressure from a few millimeters to about 10 atmospheres). The lamps caninclude envelopes capable of transmitting light of a wavelength of atleast 150 nm and up to and including 700 nm or typically at least 240 nmand up to and including 450 nm. The lamp envelope can consist of quartz,such as spectrocil or Pyrex. Typical lamps that can be employed forproviding ultraviolet radiation are, for example, medium pressuremercury arcs, such as the GE H3T7 arc and a Hanovia 450 W arc lamp.Silver ion photoreducing and any photocuring can be carried out using acombination of various lamps, some of or all of which can operate in aninert atmosphere. When using UV lamps, the irradiation flux impingingupon the substrate (or applied layer or pattern) can be at least 0.01watts/inch² (0.0197 watts/cm²) to effect sufficient rapid silver ionphotoreduction and photocuring of the applied non-aqueous metalcatalytic composition within 1 to 20 seconds in a continuous manner, forexample in a roll-to-roll operation.

An LED irradiation device to be used in the photoreduction andphotocuring can have an emission peak wavelength of 350 nm or more. TheLED device can include two or more types of elements having differentemission peak wavelengths greater than or equal to 350 nm. A commercialexample of an LED device that has an emission peak wavelength of 350 nmor more and has an ultraviolet light-emitting diode (UV-LED), isNCCU-033 that is available from Nichia Corporation.

The result of such irradiation of a precursor article is an intermediatearticle comprising the substrate (for example, individual sheets or acontinuous web) and having thereon either a photoreduced and photocuredmetal catalytic layer or a photoreduced or photocured metal catalyticpattern (containing suitable silver particles) on one or both supportingsides of the substrate, each of which is derived from a non-aqueousmetal catalytic composition as described above.

The resulting intermediate articles can be used in this form for someapplications, but in most embodiments, they are further processed toincorporate a conductive metal on the uniform photoreduced andphotocured metal catalytic layer or photoreduced and cured metalcatalytic pattern, each of which includes at least the silver metalparticles as “seed” materials for further application of metals, such asusing electroless metal procedures. For example, photoreduced andphotocured metal catalytic layer or photoreduced and photocured metalcatalytic pattern can include other “seed” metal particles besides the“seed” silver metal particles, including but not limited to, palladium,copper, nickel, and platinum particles, all of which particles can beelectrolessly plated with copper, platinum, palladium, or other metalsdescribed below.

One useful method of this invention uses multiple flexographic printingplates (for example, prepared as described above) in a stack in aprinting station wherein each stack has its own printing plate cylinderso that each flexographic printing plate is used to print individualsubstrates, or the stack of printing plates can be used to printmultiple portions in a substrate web (on one or both opposing supportingsides). The same or different non-aqueous metal catalytic compositioncan be “printed” or applied to a substrate (on same or opposingsupporting sides) using the multiple flexographic printing plates.

In other embodiments, a central impression cylinder can be used with asingle impression cylinder mounted on a printing press frame. As thesubstrate (or receiver element) enters the printing press frame, it isbrought into contact with the impression cylinder and the appropriatemetal catalytic pattern is printed (formed) using the non-aqueous metalcatalytic composition.

Alternatively, an in-line flexographic printing process can be utilizedin which the printing stations are arranged in a horizontal line and aredriven by a common line shaft. The printing stations can be coupled toexposure stations, cutting stations, folders, and other post-processingequipment. A skilled worker could be readily determined other usefulconfigurations of equipment and stations using information that isavailable in the art. For example, an in-the-round imaging process isdescribed in WO 2013/063084 (Jin et al.).

The intermediate article can be stored with just the metal catalyticlayer or metal catalytic pattern comprising the silver particles for useat a later time.

The intermediate article described herein formed after photoreducing thereducible silver ions to silver particles, can be immediately immersedin an aqueous-based electroless metal plating bath or solution toelectrolessly plate a suitable metal onto the silver particles in themetal catalytic layer or the metal catalytic pattern.

In other embodiments, after photoreducing the reducible silver ions tosilver particles, surface coating is washed with an alcohol such asmethanol, ethanol, isopropanol, or any other useful water-miscibleorganic solvent, or mixture thereof, and electroless plating can becarried out subsequently. Thus, the intermediate article can becontacted with an electroless plating metal that is the same as ordifferent from the “seed” silver metal particles described above. Inmost embodiments, the electroless plating metal is a metal differentfrom silver metal particles.

Any metal that will likely electrolessly “plate” on the silver metalparticles can be used at this point, but in most embodiments, theelectroless plating metal can be for example copper(II), silver(I),gold(IV), palladium(II), platinum(II), nickel(II), chromium(II), andcombinations thereof. Copper(II), silver(I), and nickel(II) areparticularly useful electroless plating metals.

The one or more electroless plating metals can be present in anaqueous-based electroless plating bath or solution in an amount of atleast 0.01 weight % and up to and including 20 weight % based on totalsolution weight.

Electroless plating can be carried out using known temperature and timeconditions, as such conditions are well known in various textbooks andscientific literature. It is also known to include various additivessuch as metal complexing agents or stabilizing agents in theaqueous-based electroless plating solutions. Variations in time andtemperature can be used to change the metal electroless platingthickness or the metal electroless plating deposition rate.

A useful aqueous-based electroless plating solution or bath is anelectroless copper(II) plating bath that contains formaldehyde as areducing agent. Ethylenediaminetetraacetic acid (EDTA) or salts thereofcan be present as a copper complexing agent. For example, copperelectroless plating can be carried out at room temperature for severalseconds and up to several hours depending upon the desired depositionrate and plating rate and plating metal thickness.

Other useful aqueous-based electroless plating solutions or bathscomprise silver(I) with EDTA and sodium tartrate, silver(I) with ammoniaand glucose, copper(II) with EDTA and dimethylamineborane, copper(II)with citrate and hypophosphite, nickel(II) with lactic acid, aceticacid, and a hypophosphite, and other industry standard aqueous-basedelectroless baths or solutions such as those described by Mallory et al.in Electroless Plating: Fundamentals and Applications 1990.

After the electroless plating procedure to provide a conductive metallayer or a conductive metal pattern on one or more portions of one oropposing supporting sides of the substrate, the resulting productarticle can be removed from the aqueous-based electroless plating bathor solution and again washed using distilled water or deionized water oranother aqueous-based solution to remove any residual electrolessplating chemistry. At this point, the electrolessly plated metal isgenerally stable and can be used for its intended purpose.

In some embodiments, the resulting product article can be rinsed orcleaned with water at room temperature as described for example in[0048] of WO 2013/063183 (Petcavich), or with deionized water at atemperature of less than 70° C. as described in [0027] of WO 2013/169345(Ramakrishnan et al.).

Thus, a method of this invention can be used to provide a productarticle comprising a substrate and having disposed thereon one or moreelectrically-conductive patterns (on either or both supporting sides)comprising electrically-conductive metals acquired by providing “seed”silver metal particles by in-situ reduction of silver ions followed byelectroless plating with more silver or with a different metal.

To change the surface of the electrolessly plated metal for visual ordurability reasons, it is possible that a variety of post-treatments canbe employed including surface plating of still at least another (thirdor more) metal such as nickel or silver on the first electrolesslyplated metal (this procedure is sometimes known as “capping”), or thecreation of a metal oxide, metal sulfide, or a metal selenide layer thatis adequate to change the surface color and scattering propertieswithout reducing the electrical conductivity of any electrolessly platedmetal. Depending upon the metals used in the various capping procedures,it may be desirable to treat the electrolessly plated metal with a seedmetal catalyst in an aqueous-based seed metal catalyst solution tofacilitate deposition of additional metals.

In addition, multiple treatments with the same or differentaqueous-based electroless metal plating solution can be carried out insequence, using the same or different conditions. Sequential washing orrinsing steps can be also carried out where appropriate at roomtemperature or a temperature less than 70° C.

In some embodiments, a method for providing an electrically-conductiveproduct article comprises:

-   -   providing a continuous web of a transparent substrate of any of        those materials described above, but particularly transparent        polymeric substrates,    -   providing a metal catalytic pattern on one or more portions of        the continuous web using a non-aqueous metal catalytic        composition as described above, for example applying it using a        flexographic printing member,    -   exposing the metal catalytic pattern to radiation (as described        above) to reduce the silver ions (photoreduction) and optionally        photocure photocurable components in the non-aqueous metal        catalytic composition in the one or more portions of the        continuous web, and    -   electrolessly plating the non-aqueous metal catalytic        composition in the one or more portions of the continuous web        with an electrically conductive metal, using electroless plating        procedures described above.

Embodiments of this method can be carried out on only one of thesupporting sides of the transparent substrate, or on both supportingsides of the transparent substrate to provide the same or differentelectrically-conductive patterns of electrically conductive metals.

As would be apparent to one skilled in the art, a plurality of portionshaving the same or different electrically-conductive patterns can beprovided on this continuous web (on one or both supporting sides)according to the present invention.

For example, a method for providing a plurality of product articlescomprises:

-   -   providing a continuous web of a transparent substrate,    -   forming a metal catalytic pattern on at least a first portion of        the continuous web using a non-aqueous metal catalytic        composition as described above,    -   exposing the metal catalytic pattern to photoreducing radiation        (as described above) to form silver metal particles in the first        portion of the continuous web (which first portion can also        contain photocured materials),    -   electrolessly plating the silver metal particles in the first        portion of the continuous web with an electrically conductive        metal (as described above), and    -   repeating these features on one or more additional portions of        the continuous web that are different from the first portion,        using the same or different non-aqueous metal catalytic        composition.

The exposure to photoreducing radiation can be carried out by advancingthe continuous web comprising the first portion comprising the metalcatalytic pattern to be proximate exposing radiation, and therebyphotoreducing the silver ions. Second and additional portions can besimilarly advanced on the continuous web to be proximate exposingradiation to reduce the reducible silver ions in each of the portions.Electroless plating can be carried out immediately, of if desired, theresulting continuous web comprising multiple metal catalytic patternswith silver metal particles can be wound up as a roll for future use.

As would be apparent from other teaching in this disclosure, such methodembodiments can be carried out on opposing supporting sides of thecontinuous web to provide same or different metal catalytic patterns.

The multiple electrically-conductive patterns provided by electrolesslyplating the metal catalytic patterns can be used to form individual ormultiple electrically conductive articles from the continuous web andsuch electrically-conductive articles can be assembled into the same ordifferent individual devices.

Thus, useful product articles prepared according to the presentinvention can be formulated into capacitive touch screen sensors thatcomprise suitable electrically-conductive grid lines in touch regions,electrodes, electrical leads, and electrically-conductive connectorsthat provide connection of electrically-conductive grids with othercomponents of a device.

Some details of useful methods and apparatus for carrying out thesefeatures are described for example in WO 2013/063183 (Petcavich), WO2013/169345 (Ramakrishnan et al.). Other details of a usefulmanufacturing system for preparing electrically-conductive articlesespecially in a roll-to-roll manner are provided in PCT/US/062366, filedOct. 29, 2012 by Petcavich and Jin, the disclosure of which isincorporated herein by reference.

An additional system of equipment and step features that can be used incarrying out the present invention is described in U.S. Ser. No.14/146,867 filed Jan. 3, 2014 by Shifley, the disclosure of which isincorporated herein by reference for all details that are pertinent tothe present invention.

The present invention provides at least the following embodiments andcombinations thereof, but other combinations of features are consideredto be within the present invention as a skilled artisan would appreciatefrom the teaching of this disclosure:

-   -   1. A method for providing an article, comprising:        -   providing a metal catalytic layer or a metal catalytic            pattern composed of a non-aqueous metal catalytic            composition on a substrate, the non-aqueous metal catalytic            composition comprising:            -   (a) a silver complex comprising reducible silver ions,                in an amount of at least 2 weight %,            -   (b) an organic phosphite in an amount of at least 2                weight %,            -   (c) an oxyazinium salt silver ion photoreducing agent in                an amount of at least 2 weight %,            -   (d) a hindered pyridine in an amount of at least 5                weight %,            -   (e) a photocurable component, non-curable polymer, or                combination of a photocurable component and a                non-curable polymer, and            -   (f) a photosensitizer different from all components (a)                through (e) in the non-aqueous metal catalytic                composition, in an amount of at least 1 weight %,        -   all amounts being based on the total amount of            components (a) through (f) in the non-aqueous metal            catalytic composition,        -   to provide a precursor article comprising the metal            catalytic layer or the metal catalytic pattern composed of            the non-aqueous metal catalytic composition.    -   2. The method of embodiment 1, further comprising:        -   photoreducing the reducible silver ions to silver particles            in the metal catalytic layer or the metal catalytic pattern.    -   3. The method of embodiment 2, comprising:        -   photoreducing the reducible silver ions to silver particles            in the metal catalytic layer or metal catalytic pattern in            the presence of oxygen.    -   4. The method of embodiment 2 or 3, comprising:        -   photoreducing the reducible silver ions to silver particles            in the metal catalytic layer or metal catalytic pattern by            imagewise exposure of the precursor article to radiation            having a wavelength of at least 150 nm and up to and            including 700 nm.    -   5. The method of any of embodiments 1 to 4, wherein the organic        phosphite is represented by the formula:        (R′O)₃P        wherein the multiple R′ groups are the same or different        substituted or unsubstituted alkyl groups or substituted or        unsubstituted aryl groups, or two or three R′ groups can form a        substituted or unsubstituted cyclic aliphatic ring or fused ring        system.    -   6. The method of any of embodiments 1 to 4, wherein the organic        phosphite is trimethyl phosphite, triethyl phosphite, tripropyl        phosphite, tributyl phosphite, triisopropyl phosphite,        triisobutyl phosphite, triamyl phosphite, trihexyl phosphite,        trioctyl phosphite, trinonyl phosphite, tri-(ethylene glycol)        phosphite, tri-(propylene glycol) phosphite, tri(isopropylene        glycol) phosphite, tri-(butylene glycol) phosphite,        tri-(isobutylene glycol) phosphite, tri-(pentylene glycol)        phosphite, tri-(hexylene glycol) phosphite, tri-(nonylene        glycol) phosphite, tri-(diethylene glycol) phosphite,        tri-(triethylene glycol) phosphite, tri-(polyethylene glycol)        phosphite, tri-(polypropylene glycol) phosphite, or        tri-(polybutylene glycol) phosphite, or a mixture thereof.    -   7. The method of any of embodiments 1 to 6, wherein the silver        complex is silver nitrate, silver acetate, silver benzoate,        silver nitrite, silver oxide, silver sulfate, silver        thiocyanate, silver carbonate, silver myristate, silver citrate,        silver phenylacetate, silver malonate, silver succinate, silver        adipate, silver phosphate, silver perchlorate, silver        tetrafluoroborate, silver acetylacetonate, silver lactate,        silver oxalate, silver 2-phenylpyridine, and derivatives        thereof. Other useful silver complexes include silver fluoride        complexes such as silver (I) fluorosulfate, silver (I)        trifluoroacetate, silver (I) trifluoromethane sulfate,        silver (I) pentafluoropropionate, and silver (I)        heptafluorobutyrate; β-carbonyl ketone silver (I) complexes, a        silver protein, or a combination thereof.    -   8. The method of any of embodiments 1 to 7, wherein the silver        complex is present in the non-aqueous metal catalytic        composition in an amount of at least 10 weight % and up to and        including 25 weight %, based on the total amount of        components (a) through (f) in the non-aqueous metal catalytic        composition.    -   9. The method of any of embodiments 1 to 8, wherein the        oxyazinium salt silver ion photoreducing agent is one or more of        the oxyazinium salt compounds OZ-1 through OZ-16 in the        following TABLE I:

TABLE I OZ-1

OZ-2

OZ-3

OZ-4

OZ-5

OZ-6

OZ-7

OZ-8

OZ-9

OZ-10

OZ-11

OZ-12

OZ-13

OZ-14

OZ-15

OZ-16

-   -   10. The method of any of embodiments 1 to 9, wherein the        photosensitizer is a ketocoumarin, xanthone, thioxanthone,        arylketone, polycyclic aromatic hydrocarbon, or combination        thereof.    -   11. The method of any of embodiments 2 to 10, comprising:    -   photoreducing the reducible silver ions to silver particles        having an average particle size of at least 10 nm and up to and        including 1000 nm and at least 80% of the number of the silver        particles have a particle size of at least 10 nm and up to and        including 100 nm.    -   12. The method of any of embodiments 2 to 11, further        comprising, after photoreducing the reducible silver ions to        silver particles:        -   electrolessly plating a metal onto the silver particles in            the metal catalytic layer or metal catalytic pattern.    -   13. The method of any of embodiments 2 to 12, further        comprising, after photoreducing the reducible silver ions to        silver particles:        -   removing organic phosphite from the metal catalytic layer or            metal catalytic pattern, and        -   electrolessly plating a metal other than silver onto the            silver particles in the metal catalytic layer or metal            catalytic pattern.    -   14. The method of any of embodiments 1 to 13, wherein the        non-aqueous metal catalytic composition further comprises an        inert organic solvent.    -   15. The method of any of embodiments 1 to 14, wherein the        photocurable component or non-curable polymer acts as an organic        solvent medium and no inert organic solvents are purposely added        to the non-aqueous metal catalytic composition.    -   16. The method of any of embodiments 1 to 15, wherein the        non-aqueous metal catalytic composition comprises:        -   (a) the silver complex comprising reducible silver ions, in            an amount of at least 2 weight % and up to and including 90            weight %,        -   (b) the organic phosphite is present in an amount of at            least 2 weight % and up to and including 10 weight %,        -   (c) the oxyazinium salt silver ion photoreducing agent in an            amount of at least 2 weight % and up to and including 25            weight %,        -   (d) the hindered pyridine is present in an amount of at            least 5 weight % and up to and including 20 weight %,        -   (e) the photocurable component, non-curable polymer, or            combination of a photocurable component and non-curable            polymer, is present in an amount of at least 10 weight % and            up to and including 88 weight %, and        -   (f) the photosensitizer is present in an amount of at least            1 weight % and up to and including 10 weight %,        -   all amounts based on the total amount of components (a)            through (f) in the non-aqueous metal catalytic composition.

The following Examples are provided to illustrate the practice of thisinvention and are not meant to be limiting in any manner.

Preparation of a Comparative Composition Containing Silver Nitrate

To a mixture of ethoxylated diacrylate (0.5 g, SR259 from Sartomer) andethoxylated pentaerythritol tetraacrylate (0.167 g, SR 494 fromSartomer), photoinitiator and photoreducing agent2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone (0.02 g,S9) was added and dissolved at room temperature by sonication in anultrasound bath. To this mixture, a silver nitrate solution (0.4 ml,0.67 g) was added and dissolved by stirring in the dark. In two hours,the viscosity of the formulation significantly increased and in the next2-3 hours, the formulation gelled completely.

Inventive Example 1

This example demonstrates the use of a non-aqueous metal catalyticcomposition comprising a silver complex and an oxyazinium salt silverion photoreducing agent for the generation of silver particles.

To a mixture of 1,1,1-trimethylolpropane triacrylate (1.66 g, SR351,Sartomer) and ethoxylated (30) bisphenol A dimethacrylate (3.33 g, SR9036A, Sartomer), photoinitiator and silver ion photoreducingcomposition 4-phenyl-N-methoxypyridinium tetrafluoroborate (0.4 g, ˜6weight %), photosensitizer 2-chlorothixanthone (1 weight %), andhindered pyridine 2-phenylpyridine (2-4 weight %) were added anddissolved at room temperature in an ultrasound bath. To this mixture,the Ag(2-phenylpyridine)₂ ⁺.NO₃ ⁻ complex described above (1 g, ˜10weight %) dissolved in chloroform (0.7 ml) was added and dissolved bystirring in the dark to form a non-aqueous metal catalytic compositionaccording to this invention.

This non-aqueous metal catalytic composition was spin coated ontopoly(ethylene terephthalate) film substrates at 1500 rpm for 30 secondsto form precursor articles that were then exposed to UV light from amedium pressure Hg/Xe lamp for varying lengths of time to formintermediate articles. During exposure, the coatings changed color fromcolorless to yellow. An absorption spectrum of each coating wasrecorded, showing a clear plasmonic band at 420 nm due to formation ofsilver particles as shown in FIG. 1.

Electroless Copper Plating

Each intermediate article described above was immersed in an electrolesscopper plating bath solution from ENTHONE® (Enplate LDS CU-406 SC) at45° C. for 15 minutes using conditions recommended by the commercialsupplier to provide product articles. Each product article was taken outof the bath, rinsed with water, and dried. A clear coating of metalliccopper was observed on the surface of the product article.

Inventive Example 2

This example demonstrates the flexographic printing and electrolesscopper plating of a non-aqueous metal catalytic composition comprising asilver complex and an oxyazinium salt silver ion photoreducingcomposition for in-situ generation of silver particles.

Fine lines of nominal width 7-10 μm of the non-aqueous metal catalyticcomposition described in Invention Example 1 were printed onpoly(ethylene terephthalate) film substrate to provide a precursorarticle. Printing of the fine lines was carried out using a flexographicIGT F1 printer and a flexographic printing member obtained from acommercially available Kodak Flexcel NX photopolymer plate. The appliedpattern of non-aqueous metal catalytic composition was imaged through amask that was written using the Kodak Square Spot laser technology at aresolution of 12,800 dpi. Exposure was carried out using with UV lightusing Fusion benchtop conveyor unit equipped with H-bulb. The nominal UVdose was between 50-100 mJ/cm².

After UV exposure, the resulting intermediate article was immersed in anelectroless copper plating bath solution, ENTHONE® Enplate LDS CU-406SC, at 45° C. for 15 minutes using conditions recommended by thecommercial supplier. The resulting product article was taken out of thebath, rinsed with water, and dried. Micrographs of the printedelectrically-conductive pattern showed a clear coating of metalliccopper in printed lines (see HG. 2).

The invention has been described in detail with particular reference tocertain preferred embodiments thereof, but it will be understood thatvariations and modifications can be effected within the spirit and scopeof the invention.

The invention claimed is:
 1. A method for providing an article,comprising: providing a metal catalytic pattern composed of anon-aqueous metal catalytic composition on a substrate, the non-aqueousmetal catalytic composition comprising, in admixture: (a) a silvercomplex comprising reducible silver ions, in an amount of at least 2weight % and up to and including 25 weight %, wherein the silver complexis silver acetate, silver benzoate, silver nitrite, silver oxide, silversulfate, silver thiocyanate, silver carbonate, silver myristate, silvercitrate, silver phenylacetate, silver malonate, silver succinate, silveradipate, silver phosphate, silver perchlorate, silver tetrafluoroborate,silver acetylacetonate, silver lactate, silver oxalate, silver2-phenylpyridine; a silver fluoride complex; a β-carbonyl ketone silver(I) complex; a silver protein; or a combination thereof, (b) an organicphosphite in an amount of at least 2 weight % and up to and including 10weight %, wherein the organic phosphite is tri-iso-propyl phosphite, trin-butyl phosphite, tri-iso-propyl phosphite, tri-iso-butyl phosphite,triamyl phosphite, tri-n-hexyl phosphite, tri-n-octyl phosphite,tri-n-nonyl phosphite, tri(ethylene glycol) phosphite, tri(propyleneglycol) phosphite, tri(iso-propylene glycol) phosphite, tri(n-butyleneglycol) phosphite, tri(iso-butylene glycol) phosphite, tri(n-pentyleneglycol) phosphite, tri(n-hexylene glycol) phosphite, tri(n-nonyleneglycol) phosphite, tri(diethylene glycol) phosphite, tri(triethyleneglycol) phosphite, tri(polyethylene glycol) phosphite, tri(polypropyleneglycol) phosphite, or tri(polybutylene glycol) phosphite, or a mixturethereof, (c) an oxyazinium salt silver ion photoreducing agent in anamount of at least 2 weight % and up to and including 25 weight %, (d) ahindered pyridine in an amount of at least 5 weight % and up to andincluding 20 weight %, wherein the hindered pyridine in a compoundhaving an alkyl group having 1 to 18 carbon atoms, a phenyl group or anaphthyl group in an ortho position on the pyridine ring (e) aphotocurable component, non-curable polymer, or combination of aphotocurable component and a non-curable polymer in an amount of atleast 10 weight % and up to and including 88 weight %, and (f) aphotosensitizer different from all components (a) through (e) in thenon-aqueous metal catalytic composition, in an amount of at least 1weight % and up to and including 10 weight %, all amounts being based onthe total amount of components (a) through (f) in the non-aqueous metalcatalytic composition, to provide a precursor article comprising themetal catalytic pattern composed of the non-aqueous metal catalyticcomposition; photoreducing the reducible silver ions to silver particlesin the metal catalytic pattern by imagewise exposure of the precursorarticle to radiation having a wavelength of at least 150 nm and up toand including 700 nm; the method further comprising: electrolesslyplating a metal other than silver onto the silver particles in the metalcatalytic pattern, or removing organic phosphite from metal catalyticpattern, and electrolessly plating a metal other than silver onto thesilver particles in the metal catalytic pattern, wherein the oxyaziniumsalt silver ion photoreducing agent is one or more of the oxyaziniumsalt compounds OZ-1 through OZ-16 in the following TABLE I: TABLE I OZ-1

OZ-2

OZ-3

OZ-4

OZ-5

OZ-6

OZ-7

OZ-8

OZ-9

OZ-10

OZ-11

OZ-12

OZ-13

OZ-14

OZ-15

OZ-16


2. The method of claim 1, comprising: photoreducing the reducible silverions to silver particles in the metal catalytic pattern in the presenceof oxygen.
 3. The method of claim 1, wherein the photosensitizer is aketocoumarin, xanthone, thioxanthone, arylketone, polycyclic aromatichydrocarbon, or combination thereof.
 4. The method of claim 1,comprising: photoreducing the reducible silver ions to silver particleshaving an average particle size of at least 10 nm and up to andincluding 1000 nm and at least 80% of the number of the silver particleshave a particle size of at least 10 nm and up to and including 100 nm.5. The method of claim 1, wherein the non-aqueous metal catalyticcomposition further comprises an organic solvent that is acetone,dichloromethane, isopropanol, dipropylene glycol methyl ether, ethyleneglycol, chloroform, methanol, ethanol, isopropanol,1-methoxy-2-propanol, methylene chloride, or a mixture thereof.
 6. Themethod of claim 1, wherein the photocurable component or non-curablepolymer acts as an organic solvent medium.
 7. The method of claim 1,wherein the metal catalytic pattern is provided on the substrate byinkjet printing or flexographic printing.